docgatorx8er

iTrader: (10)

The problem with this solution for wheel2wheel racing is two-fold.
1. Many classes do not allow removal of the exhaust shroud. It is considered an aero mod.
2. You don't want the exhaust to protrude past the bumper. We get bumped alot. If hit, bending the exhaust would cause constriction.

Borla is making the XR1 for the rotary. They are all available now.

Parts are
400371 - Oval - 16"
400372 - Oval - 12"
400373 - Round - 16"

TeamRX8

iTrader: (25)

The ultralight race mufflers from Coast Fabrication work great and are light. I found some lightweight packing that works well with them too, but the US distributor dropped out and now it has to be ordered from Germany.

marka

Howdy,

For stock class autox, does anyone have a reference as to weight and noise level for the catback solutions out there?

Sounds like they are:

Stock: 39 lbs

Isley / similar custom setup

Racing Beat Race Exhaust: 25.5 lbs, ~$600, 92db @50'

HKS Hi-Power: ~$600

Anyone have data on the Hi Power & Isely approach?

This is on the list for winter improvements.

Mark

TeamRX8

iTrader: (25)

C'mon Mark , always with the noob-schmuck questions ...

RX-8 Racing - RX8Club.com

marka

Howdy,

Half the time I search here I end up with some post where I have no clue who the person is, if they're talking about an STX exhaust, or whatever else.

I was sorta hoping that someone would shortcut that.

But yes, I'll search more anyway.

:-)

Mark

TeamRX8

iTrader: (25)

Like you got your shortcut tire question answer? Keep on failing bro ...

STX exhaust = how light is it, how loud is it, how much am I willing to spend

.

Orthonormal

M.A.: I just had an Isley style axle-back muffler installed. The main difference is that I substituted a Magnaflow 18x5x8 2.5" stainless muffler for the Borla that Jason used. I weighed the stock S2 muffler that we cut off, and it was 31 Lbs. I weighed the components for the replacement and estimate that it's around 15 pounds. Definitely under 17 (total weight of components before cutting) and more than 12 (weight of the muffler with no pipes attached).

I suspect that the weight estimates for the stock and the RB mufflers that you've seen both include the mid pipe.

Photo of new muffler setup

marka

Howdy,

That looks really nice!

Its looking like for cost & weight reasons both its better to go with an Isley style setup like this. But the open question is "which muffler?"

The rotary specific XR-1's from Borla are both pricey and have a 3" in/out, which would seem to make stuff harder than it needs to be. The 16" case XR-1 that Jason used isn't nearly as bad, but the Magnaflow you used looks to be a decent bit cheaper.

How's the sound level for daily driving? Drone-y at all?

edit: That's the 18" case muffler, right?

edit #2: That one uses packing, right? Does the XR-1 use packing as well? I'm wondering if packing in the muffler will eventually cause it to get louder.

Mark

TeamRX8

iTrader: (25)

The S1 catback exhaust weighs ~39

All this information has been hashed and rehashed a million times on this forum. You can build a catback exhaust as light as 10 lbs (single muffler/tip) or 16 lbs (dual mufflers/tips) that will make sound. If you are worried about drone you can cut a flange in on the OE exhaust so that it can drop out easily on race day and then have the lightweight race exhaust attach there.

marka

Howdy,

Really?

Ok. Find me the thread that talks about the sound & weight differences between the MagnaFlow 18" case and Borla XR-1 16" case mufflers.

Because I haven't found it.

Mark

fossumja

iTrader: (4)

Mark,
I had the Hi-Power for a while and really liked it. It is a few pounds heavier than an Isley set up (~22lbs) due to the thick pipes and flanges. I switched to the Isley setup because I couldn't fit a trailer hitch with the Hi-Power. Both are livable for DD use and quiet on the highway (with the stock cat!).

Jim

TeamRX8

iTrader: (25)

Quieter than an open pipe maybe and will make sound, but I never considered them to be that quiet. They all drone under certain conditions. The only quiet and light exhaust I have experienced is the JIC full Ti catback which is NLA and quite a rare find

Therein is the rub. Sound and its acceptable level is a personal preference. Some people don't consider the open pipe to be loud. Your wife and kids might scream over anything other than the OE exhaust.

TeamRX8

iTrader: (25)

Well if you want to redefine the topic to that specific point, the answer is it doesn't exist. Why don't you go do and directly compare both so that the next person can have it handed to them simple and easy.

You originally brought up two other exhausts for which there is tons of info on both. Further, did you even read this thread? It's not even the correct place to have started your inquiry

marka

Howdy,



Mark

tpdrx8

https://www.rx8club.com/rx-8-racing-...onuses-108464/

Looks like I saved 23lbs . . .

Orthonormal

Here's what I got from Summit Racing
1x MPE-12246 MUFFLER (Magnaflow 12246)
1x WLK-36484 DYNOMAX STAINLESS STEEL TIPS (Dynomax 36484 tip)
2x WLK-42392 EXHAUST PIPE ADAPTOR (3 1/2" radius J-bend)

I got the Magnaflow because a friend with an RX-8 told me he liked the sound inside the car better than the Borla. His father in law decided to replace his own Borla with the same Magnaflow. So a pretty good endorsement, and it does sound pretty good and is quiet with the windows up. It's pretty quiet at neutral throttle but louder than stock if you give it some gas, like if you're going up a slight grade.

Because the body is longer than the Borla, it will be harder to get it tucked away so that the frame rail is unobstructed for the standard trailer hitch mounting, but I don't plan to get one of those hitches. They have a tendency to screw up your trunk anyway...

I trimmed 2" off the inlet pipe to the muffler to keep it inboard enough to place the hangers correctly and leave enough room for the outlet bend.

The hangers were made from 1/2" steel rod from Lowe's, bent 90 degrees. I think you could save a few ounces if you use tube, but you'll have to figure out how to bend it without wrecking the strength. Fender washers welded on one side of the rubber grommets, hose clamps on the other side.

I got three 2.5" 3-bolt flanges and two gaskets from www.racepartsolutions.com, and got some 12mm high temp bolts and nuts from McMaster Carr, so I can swap the stock muffler back on if I ever sell the car, or swap to a turn-down if I feel the need to lose another 15 pounds. The flanges might add about a pound, which you could save if you just weld onto the mid-pipe.

The metal tab on the left side is to mount the ground strap if your car has one. Mine did, so I got a longer strap from McMaster Carr.

marka

Howdy,

Thanks John! That looks like the path I'll follow.

Did you have enough "left over" from the J bend to do the muffler exit bend as well then?

Mark

Orthonormal

Small detail: that should have said two j-bends.

Orthonormal

I pulled off the muffler to clean the bronze color off the tip. Magnaflow's FAQ says it's due to metal particles in the polishing compound used in manufacturing. They recommended Eagle1 chrome wheel cleaner to remove it without depositing new particles. I would recommend getting the cleaner and using it on the tip before you build the muffler and install it on the car, since you don't want to use the stuff while the muffler is on the car.

Anyway, I weighed it and the replacement unit is 17 pounds. So 14 pounds less than the stock S2 muffler.

I also took a photo with it off the car to give an undistorted view.